On Friday afternoon in Monza, Nike’s Breaking2 team held a pre-race briefing to divulge the remaining details of the attempt, which will take place Saturday morning at 5:45 a.m. local time (11:45 p.m. Eastern/8:45 p.m. Pacific on Friday). We’ll host a livestream of the attempt here; coverage will begin 15 minutes before the race start.

The first point to emphasize is that, whatever time Eliud Kipchoge, Zersenay Tadese, or Lelisa Desisa achieve tomorrow, it will not count as a world record. Just as Geoffrey Mutai’s tailwind-assisted 2:03:02 at the 2011 Boston Marathon didn’t conform to international rules, the race in Monza will violate at least one IAAF rule with its use of pacers rotating in and out of the race.

The final pacing plan involves an arrowhead formation, with six pacers forming the tip of the arrowhead while the three competitors run single-file behind. A total of 30 pacers are here, with six teams of three assigned to run up to three two-lap (4.8K) shifts. The spare pacers will be deployed if anyone gets tired or hurt, or if one of the three chosen runners falls behind and needs individual pacing.

The runners will receive fluids once during each 2.4-kilometer lap from a moped that will drive alongside them, a tactic that also appears to violate IAAF road race rules that forbid running alongside competitors to give them drinks. (In an understandable oversight, the rules don’t specifically mention mopeds.)

Another key new detail: The pace car, a specially outfitted Tesla, will maintain steady 2:00-marathon pace unless there’s a mid-race change of plan. This is a departure from earlier plans in which the driver of the car would respond to the runners’ pace in order to avoid violating rules about the use of external pacing aids.

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Dan Redding

For the most part, the revelations at the briefing confirmed what observers had expected. If anyone breaks 2:00, it will be largely thanks to the elaborate drafting plan, which Nike’s scientists estimate will confer an advantage comparable to running downhill at a 2.5 percent grade, and the Vaporfly shoes, which, according to testing at the University of Colorado, reduce energy consumption by a remarkable 4 percent on average.

For all the controversy the project has generated, it’s shaping up to be a highly anticipated “ground truth” test of theories that have been discussed among scientists for years. Can a tight arrowhead drafting plan really save appreciable amounts of energy? Do the shoe energy savings measured in the lab really translate to comparable benefits in a real-world race scenario?

One question that remains unanswered is what the runners will do if—some would say when—they begin to fall behind two-hour pace. Will they persist, kamikaze-style, stubbornly holding the pace until they simply disintegrate into a heap of bubbling lactic acid? Or will they back off ever so slightly, recalibrate, and aim for a still-noble 2:01?

It’s a big question, and it may strongly influence what message people take from this whole experiment. A 2:01 says, “Hey, that was close, let’s try again in a year or two.” A dramatic DNF says, “See, I told you it was impossible!”

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For that reason, the rational part of me hopes that, if needed, Kipchoge and crew will run conservatively and notch the fastest time possible, whatever that happens to be.

But for the sake of sheer spectacle, I can’t help hoping they go all-or-nothing. I have vivid memories of the 2000 Canadian Olympic Trials, where four runners agreed to take turns leading the men’s 5,000 meters to maximize their chances of hitting the Olympic standard. For the whole electrifying race, they alternated leads and stayed on course to qualify.

With a few laps left, one of the runners cracked and ended up missing by more than 10 seconds. Then, with just one lap to go, another runner simply ground to a halt and stepped off the track. He had put everything he had into running Olympic-standard pace for as long as possible—and unfortunately, 4,600 meters was as far as he could go. It was one of the most electrifying race moments I’ve ever seen, and a performance that everyone in attendance knew the runner would never regret.

And, for what it’s worth, the other two guys made it. One way or the other, let’s hope we see something like that tomorrow.

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